Abstract:
The main purpose of this work is to perform Lie group analysis of a pseudo-parabolic
partial di erential equation modelling solvent uptake in polymeric solids. Three di erent
sub-models for constitutive laws for the di usion coe cient and the viscosity will be
considered. Once the symmetries have been determined, they will be used to nd groupinvariant
solutions for the optimal systems of one-dimensional subalgebras obtained and
where possible, exact solutions will be obtained.